"Unite the Right" speaker Christopher Cantwell had no qualms revealing on HBO's Vice News that he had come armed to the teeth for a rally last weekend that degenerated into violence with one person dead.

With Boston bracing itself yesterday for the arrival of white supremacists like him for a "free speech rally" - and thousands of counter- protesters - what Mr Cantwell did next left police there nervous.

He tossed a bullet-proof vest, an assault rifle, and three handguns on his hotel room bed, pointed to another AK-47 in a bag,while pulling a knife from a concealed ankle holster. "I go to the gym all the time," he said. "I'm trying to make myself more capable of violence."

He also boasted of his bigotry, saying he was hoping for another leader - "somebody like Donald Trump (but) who does not give his daughter to a Jew". He then used a racial slur to describe Mr Trump's adviser and son-in-law, Mr Jared Kushner.

Mr Cantwell wore a black T-shirt inscribed with the words Radical Agenda, the name of his Internet blog and chat site. Thus far, it has not even been identified as one of 917 "hate groups" operating in the United States by the Southern Poverty Law Centre. The SPLC is a non-profit that monitors such groups and specialises in civil rights and public interest cases.

The bulk of those groups, or at least 663, fall into what the centre calls anti-government "patriot" groups like the Ku Klux Klan, white supremacists and neo-Nazis. Ohio alone boasts 27 hate groups ranging from the Aryan Strikeforce and Militant Knights of the Ku Klux Klan (KKK)to the Daily Stormer.

Such extremist groups date back to the American Civil War that ensued after states in the southern US revolted against the north when President Abraham Lincoln, a Republican, moved to end slavery. The KKK was one of the first groups to emerge after the Southern Confederacy surrendered in 1865.

Notorious for wearing white gowns and hoods to disguise their identities, burning crosses, and lynching freed slaves, the KKK ebbed and waned until officially established in 1915 to protest against the arrival of waves of Catholic and Jewish immigrants from Europe. Extremist right-wing groups from the American Nazi Party and John Birch Society also started to come and go.

Now their numbers are rising again, notes SPLC senior fellow Mark Potok. "The radical right out there is booming," he told NPR radio.

That has raised the alarm in Boston and other places where rallies are planned in the light of the news clips all week of white nationalists marching in Charlottesville the night before a sympathiser rammed people protesting against their presence with his car, killing one.

Scenes showed them carrying tiki torches reminiscent of Nazis marching in Nuremberg, Germany, in the 1930s, and Nazi and Confederate flags, and chanting "Jews will not replace us" and "Blood and soil". The latter phrase invokes a Nazi philosophy of "Blut und Boden" - that ethnic identity is based on only blood descent and where one lives.

"The SPLC has documented an explosive rise in the number of hate groups since the turn of the century, driven in part by anger over Latino immigration and demographic projections showing that whites will no longer hold majority status in the country by around 2040," says the group.

Fuelling the surge was the election of the first African-American president, Mr Barack Obama, and constant criticism of him and his policies by right-wing media such as Fox and Breitbart News and Drudge Report, and the provocative talking heads like Sean Hannity and Rush Limbaugh.

Like Islamic militants, the white nationalist hate groups use the Internet to spread their message, raise money and recruit members.

The SPLC has also blamed Mr Trump's rise for their resurgence. It said extremist groups were encouraged by his campaign pledge to bar Muslims from entering the country, his insults of Latino-Americans, and his engagement with white nationalists on Twitter.

"Trump's run for office electrified the radical right, which saw in him a champion of the idea that America is fundamentally a white man's country," writes Mr Potok. "Several new and energetic groups appeared last year that were almost entirely focused on Trump and seemed to live off his candidacy."

And some of their members are not averse to violence.

The Anti-Defamation League, a US-based international Jewish non-governmental organisation that fights anti-Semitism and other forms of bigotry, estimates that right-wing extremists were responsible for 74 per cent of all murders committed by domestic extremists in the US between 2007 and last year. That compares with 24 per cent carried out by Islamic extremists and 2 per cent by leftists.

The white nationalists - unlike neo-Nazis in Europe and Al-Qaeda and ISIS militants who cover their faces and digitise their voices - had no problem showing their faces as they brandished their weapons. As Ms Elle Reeve, the Vice News reporter who interviewed Mr Cantwell, told MSNBC, the Internet enables them to raise money fast and "they don't have to worry about getting fired for the vile beliefs".

Things have not turned out well, though, for her star whose rant has been viewed more than 30 million times on the Internet. Footage later began circulating of the muscle-bound Mr Cantwell crying after finding out a warrant had been issued for his arrest. "I don't know what to do," he says while sniffling. Now he's being mocked on the Net as the "weeping Nazi".

To add more insult to injury, Mr Cantwell's OkCupid profile advertising himself as interested in "getting married and having children" with the right woman has also been shared on social media. The dating website has now banned him for life.